The project is designed to provide information about the structure and function of neuronal mechanisms in the mammalian spinal cord which produce and control movement. These mechanisms include reflex pathways that convey sensory information from primary afferents to alpha motoneurons, interactions between different reflex pathways, modulation of information flow through reflex pathways by supraspinal descending systems, and the production of autonomous rhythmic activity by central pattern generators within the spinal cord. Electrophysiological, neuroanatomical, and computer modeling approaches are used. Recent work has emphasized examination of the modulation of transmission through excitatory cutaneous reflex pathways by the spinal central pattern generator for locomotion in order to clarify the organization of spinal interneurons that control the basic patterning of muscle activation during locomotion in the cat.